I was sort of hoping for a bare bones structure. After a little reading it appears that Removeduplicates is available to Excel 2007 and above.

First I created a simple spreadsheet with your sample data, saved and closed. Then I fired up Excel and told it to record a macro opening the spreadsheet and removing dupes. I then stopped the recording, and then viewed the code... which converted to kix is below:

 Code:
$oXL = CreateObject("EXCEL.application")
$OXL.visible=1
$RC=$oXL.workbooks.Open("D:\Excel\RemoveDuplicates\test.xlsx")
$oXL.ActiveSheet.Range("$A$1:$A$5").RemoveDuplicates(1,0)


Does this help?